In mobile communications networks, information regarding mobile subscribers are stored in databases, referred to as home location registers (HLRs) and visitor location registers (VLRs). HLRs store information about subscribers that belong to the same network as the HLR. VLRs temporarily store information about subscribers who are currently “roaming” in the area serviced by that VLR. The VLR may belong to the subscriber's home network or to a foreign network. The HLR and VLR store information needed to correctly route voice calls or data communications to the mobile subscriber. This may include international mobile station identification (IMSI), mobile identification number (MIN), mobile directory number (MDN), and mobile station international ISDN number (MSISDN), as well as the IDs of the VLR and MSC with which the subscriber is currently associated. When a mobile subscriber travels from an area controlled by one VLR or MSC to an area controlled by a different VLR or MSC, a series of messages, referred to as mobile application part (MAP) messages, are exchanged to update contact information for the mobile subscriber in the VLR and HLR. In some instances, it may be desirable for the home network service provider to send a message to the provider's subscribers who are roaming in a foreign network or to a database in response to a change in location of the subscriber. It may also be desirable for the home network service provider to send a message to a foreign subscriber (i.e., a subscriber from a different network provider) who is roaming within the network. Examples of situations in which it may be desirable to send a message to a mobile subscriber in response to a change in location of the subscriber are:                Sending a greeting or “welcome” message to the roaming subscriber;        Sending travel information, such as hotels, restaurants, etc. in the area in which the subscriber is roaming;        Sending advertising information regarding services available in the area; and        any other type of message that may be of interest to the roaming subscriber.        
Although the MAP protocol defines procedures for updating information in registers, such as HLRs and VLRs, the protocol does not specify a means for notifying a network element, such as a short message service center (SMSC) or a presence server, of a change in location of a subscriber. Moreover, the protocol does not specify a method for delivering a message to either of these entities, and thus to the subscriber, in response to a change in location of the subscriber.
Accordingly, there exists a need for novel methods and systems for generating messages in response to a change in location of a mobile subscriber.